Our major objectives are as follows: 1. To continue our search for efficient stereoselective methods of synthesizing tri- and tetra- substituted olefinic bonds, and to apply these methods to the synthesis of cyclization substrates (see 2 below), and natural products of importance, e.g., insect hormones and pheromones, plant hormones, etc. 2. (a) To study the possibility of simulating in the laboratory the types of chemical processes that are involved in the key step in the biogenesis of naturally occurring cyclic terpenoids, including the steroids. This key step is the cyclization process involving the olefinic bands which proceeds in vivo with extraordinary structural- and stereo-specificity; (b) To examine systems which are designed to shed light on the intimate mechanism of the key cyclization step in the aforementioned biosyntheses, and in particular to learn something about the specific role of the enzyme; (c) To attempt to apply non-enzymic cyclizations to the total synthesis of polycycloisoprenoid systems including steroids. 3. (a) To continue the study of certain classical type synthetic projects directed toward the production of natural products that have not yet been totally synthesized, e.g., some of the pentacyclic triterpenoids and the cevine alkaloids; (b) To exploit any especially novel behaviors and reactions encountered in the course of the aforementioned studies.